Blood oxygenator in combination with a low pressure heat exchanger

ABSTRACT

A BLOOD OXYGENATOR HAS A THIN WALL HEAT EXCHANGER SHELL, HAVING A HIGHLY THERMALLY CONDUCTIVE SHELL WALL COMPOSITION, COAXIALLY ETERIORLY DISPOSED AROUND A BLOOD OXYGEN EXCHANGE TUBULAR ARRAY. THE APEX OF THE SHELL IS TIGHTLY SEALED TO THE TOP TERMINUS OF THE TUBULAR ARRAY AND THE BASE OF THE SHELL IS TIGHTLY SEALED TO AN EXTERIORLY DISPOSED COAXIAL OXYGENATED BLOOD COLLECTOR MANIFOLD. THE INTERIOR FACE OF THE SHELL WALL ADJACENT TO THE TUBULAR ARRAY IS PROVIDED WITH A FLOWING THIN FILM HEAT TRANSFER FLUID FROM A HEAT TRANSFER FLUID CIRCULATORY MEMBER HAVING A FLUID INLET AND MULTIPLE FLUID OUTLETS. THE HEAT TRANSFER FLUID EXCHANGES THERMAL ENERGY WITH THE OXYGENATED BLOOD FLOWING DOWN THE NARROW ANNULAR VOLUME DISPOSED ON THE EXTERIOR OF THE HEAT TRANSFER SHELL.

Oct 9, 1973 R. c. BRLIJMFIELD 1 BLOOD OXYGENATOR IN COMBINATION WITH A LOW PRESSURE HEAT EXCHANGER 2 Sheets-Sheet 1 Filed Jan. 10, 1972 47 46 57 BM 1% I 1973 R. c. BRUMFIELD 3,754,271

BLOOD OXYGENATOR IN COMBINATION WITH A LOW PRESSURE HEAT EXCHANGER 2 Sheets-Sheet 2 Filed Jan. 10, 1972 United- States Patent Office 3,764,271 Patented Oct. 9, 1973 3,764,271 BLOOD OXYGENATOR IN COMBINATION WITH A LOW PRESSURE HEAT EXCHANGER Robert C. Brumfield, 73 Emerald Bay, Laguna Beach, Calif. 92657 Filed Jan. 10, 1972, Ser. No. 216,649 Int. Cl. A61m N03 US. Cl. 23-2585 18 Claims ABSTRACT OF THE DISCLOSURE A blood oxygenator has a thin wall heat exchanger shell, having a highly thermally conductive shell wall composition, coaxially exteriorly disposed around a blood oxygen exchange tubular array. The apex of the shell is tightly sealed to the top terminus of the tubular array and the base of the shell is tightly sealed to an exteriorly disposed coaxial oxygenated blood collector manifold. The interior face of the shell wall adjacent to the tubular array is provided with a flowing thin film heat transfer fluid from a heat transfer fluid circulatory member having a fluid inlet and multiple fluid outlets. The heat transfer fluid exchanges thermal energy with the oxygenated blood flowing down the narrow annular volume disposed on the exterior of the heat transfer shell.

CROSS REFERENCE TO RELATED APPLICATIONS This application is related to the following applications filed earlier by the same sole inventor:

US. patent application, Ser. No. 175,182 for Blood Oxygenator and Thermoregulator Apparatus, by Robert C. Brumfield, filed Aug. 26, 1971;

US. patent application, Ser. No. 196,458 for Blood Oxygenator Flow Guide, by Robert C. Brumfield, filed Nov. 11, 1971; and

US. patent application, Ser. No. 202,779 for Two Phase Fluid Flow Guide for Blood Oxygenator, by Robert C. Brumfield, filed Nov. 29, 1971.

BACKGROUND OF THE INVENTION Blood oxygenators useful for oxygenating patients blood in extra-corporeal circulation are classified in Class 23 Sublclass 258.5. The improvement taught in this invention is also so classified.

Blood oxygenators are increasingly used in advanced patient treatment involving radical cardial-pulmonary surgery. Such advanced surgical treatment requires increasingly close control of blood temperature as a parameter in the successful treatment of a patient. It may be desirable to lower the patient blood temperature in order to lower the body temperature prior to surgery. The lower blood temperature will reduce the gross body temperature, reducing the need for oxygen during a critical period in the surgical treatment. It also becomes a necessity to then rapidly increase the patients body temperature, by Warming the blood on a required time schedule.

In order to avoid cross contamination of patients, it is desirable to produce a single use, disposable blood oxygenator having heat exchanger improvements which enable the extra-corporeal circulating blood to be regulated in temperature as required. In a disposable blood oxygenator it is desirable to provide a heat exchanger improvement which has a minimum risk of cross contamination between the heat transfer fluid, typically water, and the patients blood. The probability of cross contamination between the patients blood and the circulating heat transfer fluid can be decreased by minimizing the pressure drop between the circulating heat transfer fluid and the patients circulating blood. Typically the water heat transfer fluid would enter the oxygenator at hospital line pressure which can range up to p.s.i. or the like.

SUMMARY OF THE INVENTION The low pressure heat exchanger of this invention is a modification particularly useful in the blood oxygenator and blood temperature regulating apparatus disclosed and taught in the above cited patent applications. This improved low pressure heat exchanger is specifically useful in a blood oxygenator apparatus having a blood oxygen exchange tubular array coaxially disposed therein. In an exchanger having a tubular array with a base and a top terminus, the heat exchanger combination has a thin wall tubular heat exchange shell coaxially disposed around the tubular array. The shell length has a first wall length section converging to an apex shell top, and the adjacent uniform tubular wall length of the shell is extended to the base of the terminus of the tubular array. A first sealing means provides a fluid impervious seal between the apex shell top terminus and the tubular array top terminus. A second sealing means provides a fluid impervious seal between the shell base terminus and the oxygenator blood collecting manifold coaxially exteriorly disposed around the tubular array base terminus. In the first heat exchanger annular volume disposed between the tubular array and the heat exchanger shell, having a first volume terminus adjacent the first sealing means and a second volume terminus adjacent the second sealing means, a heat transfer fluid circulatory member is disposed. The circulatory member provides a thin heat transfer fluid film sprayed onto the face of the first heat exchanger annular volume. The circulatory member has a heat transfer fluid inlet conduit and multiple exit orifices. External pumping means provides for the circulation of the heat transfer fluid through the fluid circulatory member onto the inner face of the heat exchanger thin wall shell, exchanging energy with the oxygenated blood which descends the exterior face of the heat exchanger shell. The rapidly flowing thin film of transfer fluid also descends the external wall of the tubular array, rapidly exchanges energy with the oxygenated blood ascending the array. The heat exchanger shell can be a plastic having a high thermally conductive filler such as graphite, which is compatible with blood. The thin wall exchanger shell can likewise be a thermally conductive metal having a blood compatible, thin organic film completely covering the exchanger wall face adjacent to the oxygenated blood. Vibratory means can be externally secured to the exterior wall of the tubular blood oxygenator, providing vibratory movement to the multiple walls of the oxygenator, further increasing the heat transfer rate. The vibratory movement can be adjusted to that value which increases heat transfer, without altering the blood structure.

Other objects and advantages of this invention are taught in the following description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT The earlier cited US. Patent applications disclose the teachings of the oxygen exchange tubular array and the concentric defoamer chamber disposed around the top terminus of the tubular array; therefore, it is unnecessary to repeat the disclosure of these earlier improvements. FIG. 1 terminates at 57 without illustrating in detail said improvements.

Referring to FIGS. 1, 2 and 3 as required in detail, the blood oxygenator is shown having a heat exchanger combination 11 coaxially exteriorly disposed around the blood oxygen exchange tubular array 12. The tubular array 12 has a base terminus 13 and a top terminus 14. A geometrically regular conical shape heat exchanger first shell 15 is coaxially disposed around the tubular array 12 adjacent the top 14 of the array. A second uniform tubular wall length 16 of the exchanger shell extends from the base 19 of the conical shell 15 to the base 20 of the tubular shell. The two members, the conical section heat exchanger shell 15, and the uniform tubular section heat exchanger shell 16 together constitute the total heat exchanger shell 17. The apex 18 of the conical heat exchanger shell 15 is secured by a fluid impervious first sealing means 22 adjacent to the tubular array top terminus 14. The base 20 of the tubular shell is sealed by a fluid impervious second sealing means 23 to the oxygenated blood collecting manifold means 24. The two members 15 and 16 of the heat exchanger shell 17 are sealed by a fluid impervious third seal means 25 at the shell joint of the two members. The fluid impervious sealing means 22, 23 and 25 are conventional O-ring seals disposed in O-ring grooves, as is well known. The base 19 of the conical shell is provided with an index step 26 facilitating alignment of the two heat exchanger members 15 and 16. Similarly, an index step 58 is provided on the blood collecting manifold means 24 for the further indexing of the tubular shell base 20. A molded collar 27 integrally secured to the manifold means 24 provides a base securing means for the tubular array 12.

The heat exchanger first annular volume is disposed between the tubular array 12 and the heat exchanger shell 17, the volume having an annular radius 32, a first volume top terminus 33 and a first volume base terminus 34. In the first annular volume 35 the heat transfer circulatory means 37 is disposed. The heat transfer circulatory means 37 comprises the helical tube 28 supportively disposed around the tubular array 12, having a coil inlet conduit 38 and a multiplicity of exit orifices 31 disposed through the coil wall. The number of individual helical coil turns 29 can be that number required to provide the necessary flow rate of heat transfer fluid 36. A terminal horizontal coil turn 30 is disposed concentric with the base 19 of the conical shell member 15, providing exit orifices 31 in the coil member 30 disposed to spray heat transfer fluid 36 onto the adjacent inner face 39 of the heat exchanger shell 17.

The heat transfer fluid as sprayed forms a thin film 40 on the inner face 39 of the heat exchanger shell 17 and on the exterior face of the tubular array 12. The rapidly descending film 40 exchanges energy with the wetted walls, which in turn exchanges energy with the blood flow ing on the opposite walls of both the heat exchanger shell 17 and the tubular array 12.

Referring to FIG. 2 in detail, the concentric disposition of the tubular array 12, the heat transfer circulatory means 37, the heat exchanger shell 17, and the exterior tubular case 42 of the blood oxygenator 10 are shown. The heat transfer fluid 36 is shown entering at the coil inlet conduit 38 and exiting from the oxygenator 10 at the fluid outlet conduit 41. The outlet conduit is secured in the manifold means 24, as earlier disclosed in the patent applications cited above. The blood inlet conduit 49 is conductively secured to the patients extra-corporeal venous blood supply tubing. The oxygenated blood outlet conduit 50 conducts the oxygenated blood reserve collected in the manifold means 44, as the oxygenated blood descends the am nular blood collecting ring 43 for the length 21 of the oxygenator 10. As previously disclosed in the cited applications, the blood manifold ring 51 provides an even distribution of venous blood through the inlet apertures 52 into the blood reservoir 60. The oxygen gas inlet conduit 56 is conductively secured to oxygen gas manifold 55, which in turn conducts oxygen gas through the multiple apertures 54 of the gas manifold plate 53 into the blood reservoir 60. In the blood reservoir 60 a two-phase mixture of blood and oxygen gas bubbles are formed which are elevated through the tubular array 12.

The break line 57 terminates the FIG. 1 above the top terminus 14 of the tubular array 12. The defoamer volume 45 shown above the tubular array 12 has been previously disclosed in the above cited patent applications. Briefly, a series of concentric annular cylinders of open celled porous foam are shown. The concentric foam layers 46, 47, 61 and 62 represent foam cylinders graduating in decreasing porosity from 10 pores per inch for cylinder 46 to 60 pores per inch or even smaller, for the exterior foam cylinder 62.

It is well known that the rate of energy exchange between two fluids on opposed sides of a heat exchange shell wall is increased by increasing the velocity of the two heat transfer fluids flowing on the wall. It is a specific improvement of this invention to provide relatively high velocity moving thin films of the oxygenated blood and the heat transfer fluid in order to maintain a high rate of heat exchange between the two fluids. In order to minimize the blood trauma and damage to the formed blood elements, it is desirable to circulate the blood with the minimum amount of turbulence. The thin annular blood collecting ring 43 satisfies this condition and provides a thin film of blood which can be more easily controlled in temperature. The rapidly circulating heat transfer fluid 40 likewise provides improved heat transfer. Additionally, it is most important to provide safety in the handling of the patients extra-corporeal blood circulation. It is required that the patients blood not be contaminated by heat transfer fluid. In most applications, the heat transfer fluid will be water, controlled within a very specific temperature range. Likewise, it is desirable to manufacture a blood oxygenator which is sufliciently inexpensive so as to be used once and thrown away, thus avoiding the problems of cleaning the oxygenator with the potential catastrophic damage which can result from cross contamination of one patients blood with another patients blood. In order to reduce the cost of the blood oxygenator and concurrently provide for patients safety from cross contamination, the heat exchange means disclosed herein provides a heat exchanger combination having substantially zero pressure drop between the patients blood and the heat transfer fluid. Thus there is a greatly diminished possibility of a high pressure leak developing in the oxygenator, which can result in water or other heat transfer fluid flowing into the patients blood. The hospital water pressure which can typically range from 50 to p.s.i., is taken across the heat transfer fluid circulatory member, which can typically be an inexpensive metal tube such as aluminum, copper or the like.

In order to maintain non-turbulent laminar downward blood flow in the annular volume 43, while increasing the heat transfer rate between blood in annular volume 43 and the heat transfer fluid 36, vibratory pumping means can be applied. Thus, in the schematic FIG. 4, a three-phase vibratory pumping means 63, 64, 65 is shown secured on the exterior case of the tubular blood oxygenator 10. The means 63, 64, 65 are typically driven by three-phase electrical power at a power level producing the vibratory frequency and displacement required to increase the downward velocity of the blood in laminar flow, without inducing turbulence. The vibratory means can be adjusted in displacement and frequency to increase the blood velocity without destroying the formed blood elements and the oxygenator structure.

The heat exchanger shell 17 is illustratively shown formed in two pieces, the conical member 15 and the tubular member 16, providing convenience in molding plastic compositions and 16. Likewise the complete heat exchanger shell 17 can be formed in a single piece, such as a thin wall aluminum or stainless steel metal spinning or the like, eliminating the need for the shell joint O-ring 25. The metal heat exchanger shell 17 can be coated with a blood compatible, thin organic film disposed over the exterior wall face of the shell which is disposed adjacent to the oxygenated blood. Typically a polyurethane film, or the like equivalent thin organic film can be used. The rate of flow of the heat transfer fluid, typically water, and the temperature of the fluid can be adapted to that value which is required for the specific application. Obviously cool or very cold water can be utilized to rapidly lower the patients blood temperature as required in accepted medical procedures, and then warm water can be supplied to again warm the patients blood as desired. Also the heat transfer fluid can be a standard refrigerant type heat transfer fluid, if it becomes necessary.

Many modifications and variations in the improvement in a low pressure heat exchanger for oxygenated blood can be made in the light of my teaching. It is therefore understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. In a blood oxygenator and blood temperature regulating apparatus having a blood oxygen exchange tubular array coaxially disposed therein, said tubular array having a base and a top terminus and a heat exchanger in combination therewith, the improvement comprising:

a thin wall tubular heat exchanger shell having a highly thermally conductive wall composition, the shell length having a first wall length section converging to an apex shell top terminus annularly disposed around and adjacent said tubular array top terminus, and an integral second uniform cross section tubular wall length section extending from the base of said first converging length section the remaining length of said tubular array to said array base terminus,

a first sealing means providing a fluid impervious seal between said apex shell top terminus and said tubular array top terminus,

a second sealing means providing a fluid impervious seal between said shell base terminus and an oxygenated blood collecting manifold means cooperatively disposed at said tubular array base terminus,

a heat exchanger first annular volume disposed between said tubular array and said heat exchanger shell, having a first volume terminus adjacent said first sealing means and a second volume terminus adjacent said second sealing means,

a heat transfer fluid circulatory member disposed in said first heat exchanger volume, providing a thin heat transfer fluid film flowing on the face of said heat exchanger shell confronting said first heat exchanger annular volume, said circulatory member having a heat transfer fluid inlet and a multiplicity of heat transfer fluid exit orifices,

whereby a heat transfer fluid circulates through said fluid circulatory member, exchanging energy with said oxygenated *blood descending the exterior face of said heat exchanger shell.

2. A combination as set forth in claim 1 wherein:

said first wall length section and said second wall length section are separate mating coaxially aligned sections, and

said aligned sections have a third sealing means disposed between said sections providing, a fluid impervious seal between said sections.

3. A combination as set forth in claim 1 wherein said heat exchanger wall section disposed between said apei shell top terminus and said base of said converging cross section is a truncated right cone.

4. A combination as set forth in claim 1, wherein said heat exchanger shell wall composition is a thermoplastic composition having a graphite filler.

5. A combination as set forth in claim 1 wherein said heat exchanger shell wall is a thermally conductive metal having a blood compatible, thin organic film completely covering the exterior wall face adjacent to said oxygenated blood.

6. A combination as set forth in claim 1 wherein said heat transfer fluid is water having a controlled temperature.

7. A combination as set forth in claim 1 wherein said heat transfer fluid circulatory member is a small diameter helical coil adjacently disposed around said oxygen exchange tubular array extending a major fraction of the length of said first heat exchanger annular volume, said coil having a multiplicity of exit orifices for said heat transfer fluid, a substantial fraction of said orifices disposed toward said heat exchanger shell interior face.

8. A combination as set forth in claim 1 wherein a vibratory means, having an adjustable vibratory amplitude, is disposed exteriorly on the exterior face of said blood oxygenator, providing vibrations in said heat exchanger shell, thereby increasing the heat transfer rate between said blood and said heat transfer fluid.

9. In a blood oxygenator and blood temperature regulating apparatus having a blood oxygen exchange tubular array coaxially disposed therein, said tubular array having a base and a top terminus and a heat exchanger in combination therewith, the improvement comprising:

a thin wall tubular heat exchanger shell having a highly thermally conductive Wall composition, the shell length having a first wall length section converging to an apex shell top terminus annularly disposed around and adjacent said tubular array top terminus, and an integral second uniform cross section tubular wall length section extending from the base of said first converging length section the remaining length of said tubular array to said array base terminus,

a first sealing means providing a fluid impervious seal between said apex shell top terminus and said tubular array top terminus, second sealing means providing a fluid impervious seal between said shell base terminus and an oxygenated blood collecting manifold means cooperatively disposed at said tubular array base terminus, heat exchanger first annular Volume disposed between said tubular array and said heat exchanger shell, having a first volume terminus adjacent said first sealing means and a second volume terminus adjacent said second sealing means,

a heat transfer tubular means disposed in said first heat exchanger annular volume, said tubular means havmg a multiplicity of exit orifices providing multiple exits for a heat transfer fluid disposed in said means, said tubular means having a heat transfer fluid inlet conduct, a substantial fraction of said exit orifices displosfid toward the interior face of said heat exchanger s e a heat transfer fluid exit conduit, conductively secured to said heat exchanger first annular volume,

a tubular case means exteriorly annularly disposed around said heat exchanger shell, providing a heat transfer second narrow annular volume for oxygenated blood descending said second annular volume,

whereby said heat transfer fluid circulates through said fluid inlet conduit into said heat transfer tubular means, flows through said multiplicity of exit orifices, provides a flowing low pressure heat transfer fluid film on the face of said heat exchanger shell adjacent said first heat exchanger annular volume, and flows out said fluid exit conduit, whereby said heat transfer fluid exchanges energy with said oxygenated blood descending said second annular heat transfer volume.

10. A combination as set forth in claim 9 wherein:

said first wall length section and said second Wall length section are separate mating coaxially aligned sections, and I said aligned sections have a third sealing means disposed between said section, providing a fluid imperviou seal between said sections.

11. A combination as set forth in claim 9, wherein said heat transfer fluid is water having a controlled temperature range.

12. A combination as set forth in claim 9, wherein said heat exchanger section disposded between said apex shell top terminus and said base of said converging cross section is a truncated right cone.

13. A combination as set forth in claim 9, wherein said heat exchanger shell Wall composition is a thermoplastic composition having a graphite filler.

14. A combination as set forth in claim 9, wherein said heat exchanger shell wall is a thermally conductive metal having a blood compatible, thin organic film completely covering the Wall face adjacent to said oxygenated blood.

15. A combination as set forth in claim 9 wherein said tubular heat transfer means is a small diameter helical coil.

16. A combination as set forth in claim 9 wherein a vibratory means, having an adjustable vibratory amplitude, is disposed exteriorly on said exterior tubular case means of said oxygenator, providing vibration in said heat exchanger shell, thereby increasing the heat transfer rate between said blood and said heat transfer fluid.

17. A combination as set forth in claim 15 wherein said helical coil is adjacently disposed around said oxygen exchange tubular array, extending a major fraction of the length of said first heat exchanger annular volume.

18. A combination as set forth in claim 15 wherein said multiplicty of exit orifices are disposed toward both said heat exchanger shell and said tubular array, said multiple exit orifices positioning heat transfer fluid over substantially all of the confronting shell and tubular array area.

References Cited UNITED STATES PATENTS 2,934,067 4/ 1960 Calvin 23258.5 3,212,499 10/1965 Koreski 23-258.5 3,291,568 12/1966 Sautter 23258.5 3,437,450 4/ 1969 Greenwood 23258.5 3,547,591 12/1970 Torres 23-258.5

OTHER REFERENCES Shumway et al.: A Mechanical Pump-Oxygenator for successful Cardiopulmonary Bypass, Surgery, v01. 40, No. 5, pp. 831-839.

BARRY 1S. RICHMAN, Primary Examiner US. Cl. X.R.

55-255, 256; l28-DIG. 3, 400'; 261--122, 124 

